Dystrophic neurites infiltrate extracellular neurofibrillary tangles in Alzheimer disease.

The neurotrophic activity of beta-amyloid protein (beta-AP) has been suggested to be responsible for the dystrophic neurites that surround beta-AP deposits in senile plaques of Alzheimer disease. The recent finding that neurofibrillary tangles (NFT) that remain as remnants in the extracellular space (E-NFT) after the death of the neuron contain beta-AP, suggested that dystrophic neurites might also be associated with E-NFT. In this study, we use a probe for E-NFT, basic fibroblast growth factor (bFGF)-binding to show that E-NFT do contain dystrophic neurites. Since these neurites contain the amyloid precursor protein whose cleavage can lead to beta-AP, they may also play a role in further beta-AP deposition in the E-NFT.